Surface studies on activated and hydrided CaNi<inf>5</inf> alloy

X-ray photoelectron spectroscopic studies on the activated pure CaNi5 alloy as well as the hydride formed at 1 atm pressure and room temperature, CaNi5H4.8, showed that on activation calcium segregates to the surface and forms the oxide, whereas most of the nickel on the surface is present in the metallic form. This indicates that the coexistance of the oxide phase and the metal phase is essential for the facile hydriding behaviour of CaNi5. © 1986 Chapman and Hall Ltd.